1. Field of the Invention
The present invention relates to a storage controller and a data erasing method for a storage device.
2. Description of the Related Art
For instance, a host computer (refer it to as a “host”, hereinafter) such as a server computer or a main frame computer manages data by using a storage controller. The storage controller is also called RAID (Redundant Array of Inexpensive Disks) system and can provide a redundant storage area to the host.
Since the data to be managed is increased year by year, the capacity of the storage is desired to be enlarged. On the other hand, as the capacity of the storage device is more increased, a data erasing time is the longer when the storage device is discarded or replaced by a new storage device. Therefore, maneuverability for a user is deteriorated. For instance, a superannuated storage device or a storage device in which errors arise frequently is replaced by a new storage device and discarded. Otherwise, a storage device having a small storage capacity may be sometimes replaced by a storage device having a large storage capacity.
The data stored in the storage device to be discarded or exchanged needs to be erased not to be read by other persons from the viewpoint of security. JP-A-2003-345526 discloses a method for erasing the data of a storage device or writing data of bit 0 in all storage areas by using a format command.